1. Field of the Invention
This invention relates to the mechanical arts. In particular, it relates to a slidable duct assembly for use in aircraft anti-icing conduit systems.
2. Discussion of the Related Art
As is well-known, jet aircraft engines provide the thrust needed to propel jet aircraft. Additionally, by redirecting a portion of the compressed, bleed air produced by the engines through a conduit system, the air can be used for a variety of other purposes. These other purposes include pressurizing, heating, and cooling the aircraft's cabin, and removing moisture from its front windows. To be effective, the conduit system must not only minimize the escape of the bleed air, but it must withstand the elevated temperatures, often in excess of 650.degree. F., of the bleed air produced by today's jet aircraft.
Another important use for the bleed air is to de-ice the aircraft wings' leading edges, wing slats, and elevons. For example, to de-ice the movable slats located on the leading edge of the aircraft wings, hot, compressed, bleed air is transferred through conduit sections from a supply duct running lengthwise in the wings' leading edge to a spray duct running lengthwise in the wings' slats. The spray duct has openings to deliver the bleed air to the interior surface of the slats.
Special considerations are involved in the anti-icing conduit systems used to de-ice movable portions of the aircraft, such as wing slats and elevons, that must undergo a wide range of motions as they are extended and then retracted. In order to track the movement of these components, the conduit system must contain at least two slidable and rotatable conduit sections. Conventional duct assemblies are formed from metallic, tubular, telescoping conduit sections. To maintain the air pressure within the assembly, each conduit section is sealed with an elastomeric seal. It is a drawback of such seals, that they become unstable, if the telescoping conduit sections extend and retract relatively long distances. Consequently, it is a desideratum to design duct assemblies containing more than two conduit sections, so that the distance any conduit duct must extend and retract is minimized. It is a drawback of such multipiece systems, however, that as the number of conduit sections increases, it becomes more and more difficult to ensure that each section will be properly positioned when the duct assembly is fully extended or retracted.
Accordingly, there has existed a definite need for an improved, slidable duct assembly which minimizes the escape of compressed air and is stable at high temperatures. There has existed a still further need for a multipiece, slidable duct assembly that maintains the proper position of each telescoping conduit section as the duct assembly extends and contracts. The present invention satisfies these and other needs and provides further related advantages.